In the welding of lengths of relatively large diameter pipe together it is necessary to clamp the pipe ends in order to hold the pipe ends in proper space relationship and in order to force the pipe ends to circular shapes, the clamps usually being applied internally of the pipes. Pipes of large diameter are rarely of true circular shapes, so that without the use of a clamping device it is difficult if not impossible to obtain a satisfactory weld connection between the ends of end-to-end sections of pipes.
Pipe clamps of the type required for this type of use are exceptionally heavily constructed and are expensive. Heretofore, it has been necessary to provide a pipe clamp apparatus for each nominal size of pipe, so that if a variety of different sizes of pipes are to be welded together end-to-end to pipes of the same size a large investment in pipe clamp apparatus is required. This invention provides a single pipe clamp apparatus which may be used with two nominal sizes of pipes, the result being that the investment in pipe clamp apparatus is substantially half what it would be using conventional pipe clamp apparatus.